global theme on agroecosystems report no....
TRANSCRIPT
677–2005
®About ICRISAT
The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is a nonprofit,non-political organization that does innovative agricultural research and capacity building forsustainable development with a wide array of partners across the globe. ICRISAT’s mission is tohelp empower 600 million poor people to overcome hunger, poverty and a degraded environment inthe dry tropics through better agriculture. ICRISAT belongs to the Alliance of Future Harvest Centersof the Consultative Group on International Agricultural Research (CGIAR).
Contact Information
ICRISAT-Patancheru(Headquarters)Patancheru 502 324Andhra Pradesh, IndiaTel +91 40 30713071Fax +91 40 [email protected]
Liaison OfficeCG Centers BlockNASC ComplexDev Prakash Shastri MargNew Delhi 110 012, IndiaTel +91 11 32472306 to 08Fax +91 11 25841294
ICRISAT-Nairobi(Regional hub ESA)PO Box 39063, Nairobi, KenyaTel +254 20 7224550Fax +254 20 [email protected]
ICRISAT-Niamey(Regional hub WCA)BP 12404Niamey, Niger (Via Paris)Tel +227 722529, 722725Fax +227 [email protected]
ICRISAT-BamakoBP 320Bamako, MaliTel +223 2223375Fax +223 [email protected]
ICRISAT-BulawayoMatopos Research StationPO Box 776,Bulawayo, ZimbabweTel +263 83 8311 to 15Fax +263 83 8253/[email protected]
ICRISAT-LilongweChitedze Agricultural Research StationPO Box 1096Lilongwe, MalawiTel +265 1 707297/071/067/057Fax +265 1 [email protected]
ICRISAT-Maputoc/o INIA, Av. das FPLM No 2698Caixa Postal 1906Maputo, MozambiqueTel +258 21 461657Fax +258 21 [email protected]
Visit us at www.icrisat.org
®
Citation: Chuc NT, Piara Singh, Srinivas K, Ramakrishna A, Chinh NT, Thang NV, Wani SP and Long TD.2006. Yield Gap Analysis of Major Rainfed Crops of Northern Vietnam Using Simulation Modeling. GlobalTheme on Agroecosystems Report No. 26 Patancheru 502 324, Andhra Pradesh, India: International CropsResearch Institute for the Semi-Arid Tropics. 40 pp.
Abstract
Total population of Vietnam is 82 million as of today. It is expected to increase to 95 million by 2010 and126 million by 2020. With increasing demand for food in future, the pressure on uplands and midlands ofnorthern Vietnam would increase to produce more food for millions of poor residing in Vietnam. Majorcrops of northern Vietnam are rice, sweet potato, maize, tea, peanut and soybean, in addition to otherannual and perennial crops. The current study investigated the potential yields; yield gaps and water balanceof maize, peanut and soybean crops, which have high potential in the region. We used crop simulationmodels of the three crops and the field data to evaluate the scope for increasing productivity and waterharvesting in the six selected provinces of northern Vietnam. Analysis of the production data revealed thatsince 1994–95 the area, production and productivity of these crops have increased substantially. Improvementsin productivity have been obtained with the introduction of improved crop varieties and management practices.However, large yield gaps still exist which are variable among districts and provinces. Overall, the yield gapis 1010 kg ha-1 for summer season and 680 kg ha-1 for spring season for soybean; 2650 kg ha-1 for springseason and 2010 kg ha-1 for autumn season for peanut; and for maize it is 1990 kg ha-1 for summer season and1650 kg ha-1 for spring season, indicating the potential for future yield improvements. Because of highrainfall in northern Vietnam, significant amount of surface runoff and deep drainage occurs leading to landdegradation. The vast potential of the rainfed areas of northern Vietnam could be harnessed through large-scale adoption of integrated genetic and natural resource management technologies in watershed contextfor increasing productivity and reducing land degradation.
This publication is part of the research projects “Participatory Watershed Management for Reducing Poverty and LandDegradation in SAT Asia” (RETA No. 6067) funded by the Asian Development Bank (ADB) and the ComprehensiveAssessment of Water Management in Agriculture (CA) and was funded in part through a grant from the Governmentof Netherlands to the International Water Management Institute in support of the Assessment.
Global Theme on AgroecosystemsReport no. 26
ICRISATInternational Crops Research Institute
for the Semi-Arid TropicsPatancheru 502 324, Andhra Pradesh, India
Asian Development Bank0401 Metro Manila
0980 Manila, The Philippines
2006
Comprehensive Assessment of Water Management in AgriculturePO Box 2075, Colombo, Sri Lanka
NT Chuc, Piara Singh, K Srinivas, A Ramakrishna, NT Chinh,NV Thang, SP Wani and TD Long
Yield Gap Analysis of Major Rainfed Crops ofNorthern Vietnam Using Simulation Modeling
®
About authorsNT Chuc Ph.D. Scholar, Vietnam Agricultural Science Institute (VASI), Thanh Tri, Hanoi,
Vietnam.
Piara Singh Principal Scientist (Soil Science), Global Theme on Agroecosystems, InternationalCrops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru502 324, Andhra Pradesh, India.
K Srinivas Senior Scientific Officer, Global Theme on Agroecosystems, ICRISAT, Patancheru502 324, Andhra Pradesh, India.
A Ramakrishna Senior Scientist (Agronomy), Global Theme on Agroecosystems, ICRISAT,Patancheru 502 324, Andhra Pradesh, India.
NT Chinh Director of Legumes, R&D Center, LRDC, VASI, Thanh Tri, Hanoi, Vietnam.
NV Thang Deputy National Project Coordinator, VASI, Thanh Tri, Hanoi, Vietnam.
SP Wani Principal Scientist (Watersheds) and Regional Theme Coordinator (Asia), GlobalTheme on Agroecosystems, ICRISAT, Patancheru 502 324, Andhra Pradesh, India.
TD Long Principal Scientist and National Project Coordinator, VASI, Thanh Tri, Hanoi, Vietnam.
AcknowledgementsThe authors would like to thank the United States Agency for International Development, theComprehensive Assessment of Water Management in Agriculture and the Asian Development Bankfor providing funding support. The authors also warmly acknowledge Drs CLL Gowda, ICRISAT andYS Ramakrishna, CRIDA, for reviewing the report.
They also thank the editorial assistance of Dr Meera Reddy and Mr KNV Satyanarayana for inputingthe comments and page setting. With the able assistance of Ms Nalini the report was typed within thestipulated time.
Contents
Introduction ........................................................................................................................... 1
Climate of northern Vietnam.......................................................................................... 2
Soils of northern Vietnam ............................................................................................... 2
Land use Systems in Vietnam ......................................................................................... 3
Province-wise Area, Production and Productivity of Crops ............................................. 4
Crop Production in Six Selected Provinces of northern Vietnam ............................................ 8
Climate and Soils ............................................................................................................ 9
Major Crops ................................................................................................................. 11
Prominent Cropping Systems ....................................................................................... 12
Area Production and Productivity of Crops in the Provinces ......................................... 12
Potential Yields and Yield Gaps of Major Crops ................................................................... 16
Traditional Method of Yield Gap Analysis ............................................................................ 16
Experimental station yields and yield gap analysis of soybean ....................................... 18
Experimental station yields and yield gap analysis of peanut ......................................... 19
Simulation Approach of Yield Gap Analysis ......................................................................... 20
Simulated potential yield and yield gap of soybean ....................................................... 21
Simulated potential yield and yield gap of peanut ......................................................... 23
Simulated potential yield and yield gap of maize .......................................................... 26
Constraints and Opportunities for Bridging the Yield Gaps .................................................. 27
References ............................................................................................................................ 28
Appendixes ........................................................................................................................... 30
1
IntroductionVietnam has a geographical area of 0.33 million km2, out of which North Vietnam covers about 0.17million km2. North Vietnam has 2.95 million ha under agriculture, which constitutes 31% of the totalagricultural land (9.4 million ha) in the country. Total population of Vietnam is 82 million and about40.1 million live in North Vietnam. In terms of total population in the country, Vietnam ranks 7th inAsia and 12th in the world. Current annual rate of population growth is 1.47%. With this rate thepopulation is expected to increase to 95 million by 2010 and 126 million by 2020 (Siem and Phien,1999). About 80% of Vietnamese population lives in rural areas, employed in agriculture, forestry,fisheries and handicrafts (General Statistics Office, 2003).
Total food production in the country is 37.8 million tons and 14.2 million tons is contributed by NorthVietnam. Of the total GDP of the country, the share of agriculture is 17.43%. Agriculture of North Vietnamcontributes 6.42% to the total GDP of Vietnam. These data indicate the importance of North Vietnam to theeconomy of the country. The massive population growth has resulted in greater urbanization with moreagricultural land being transferred to non-agricultural use. Most of the rice and peanut produced in the deltaarea is exported to UK, UAE, Canada, Iraq and Holland (FAO Trade, 1995–1999; General Statistics Office,2003). Under such circumstances pressure on uplands and midlands is increasing for food production to fulfillthe local demands and achieve food security for millions of poor residing in Vietnam. The Vietnamgovernment has now a greater challenge on hand to achieve food security by 2010. Therefore, the uplands areexpected to produce more food for meeting the local needs and supply to other regions.
Northern Vietnam comprises of approximately three-quarters of uplands (mountains and hills) andone-quarter of lowland. The per capita land area for agriculture is more than 1,840 m2 in the uplands,while in the delta region it is only 300 m2. The major crops of northern Vietnam are rice, sweet potato,maize, tea, peanut, mungbean and soybean. In the lowlands mainly annual crops are grown, while inthe uplands both annual and perennial crops are grown. In the mountains, legume crops such aspeanut, soybean and mungbean are grown after rice. These crops are important, as these are source ofoil and protein for the ethnic minority people, fodder for cattle, and also help in improving soilfertility. Tea and cassava are also common crops as these are drought tolerant and have ability to growunder poor farm management practices, poor soil fertility and low inputs. Cassava is a staple food,when rice production is low and it also provides feed for animals in the upland area.
At present crop yields in northern Vietnam are low, which are 2.98 t ha-1 for maize, 1.63 t ha-1 forpeanut and 1.22 t ha-1 for soybean. The main causes of low yields are the low adoption of improvedsoil, water, nutrient, crop and pest management practices. For enhancing productivity of the majorcrops in the region, it is important to assess their yield potential under rainfed conditions and identifyconstraints causing yield gaps. The main objectives of this study were:
i) To characterize natural resources of the six selected provinces in northern Vietnam particularlysoils and climate, in relation to crop production.
ii) To estimate potential yields of rainfed maize, soybean and peanut using crop simulation modelingapproach and research station experimental data; and
iii) To assess the yield gaps between water-limited potential yields (simulated yields or experimentalyields) and achievable yields (farmer’s yield under optimum management) and betweenachievable yields and province level yields.
The overall goal of this study was to estimate the potential contribution of northern Vietnam to thenational food basket and to assess the yield gaps for maize, soybean and peanut crops and theconstraints responsible for low yields.
2
Figure 1. Annual rainfall in northern Vietnam. Figure 2. Length of growing season in Vietnam.
Climate of northern Vietnam
Climate of northern Vietnam is monsoonal with hot and wet summers and cool, cloudy and moistwinters. Total annual rainfall in northern Vietnam ranges from 1100–3000 mm (Fig.1). Average annualtemperature is 25°C, with an average maximum of 35°C (in August) and minimum of 12°C (in January).Southwest monsoon occurs from May to October, bringing heavy rainfall and temperatures remain high.November to April is the dry season with a period of prolonged cloudiness, high humidity and light rain.
Climate of northern Vietnam can be sub-divided into four seasons, viz., spring, summer, autumn andwinter. The spring season is from February to May; summer from June to July; autumn from August toOctober; and winter from November to January. Six benchmark sites selected for yield gap analysisare located in northern Vietnam, where the maximum rainfall occurs from July to September. Juneand July are the hottest months, while December and January are the coldest months of the years.The length of growing season ranges from 180 to 365 days (Fig. 2), which provides opportunity togrow two crops in a year during spring and summer or autumn-winter.
Soils of northern Vietnam
The soils of uplands and lowlands in northern Vietnam are quite diverse. These are classified into 14groups and 68 soil types, of which 10 groups are present in the mountainous area (Siem and Phien,1999). Main soil types in northern Vietnam are ferralsols, acrisols, andosols, fluvisols, gleysols andlittle of alfisols (Fig. 3). In general, farmers use these lands mainly for cultivation of irrigated rice andrain-fed crops such as maize, sweet potato, cassava, peanut, soybean, tobacco, sugarcane and tea. Two-thirds of the uplands in northern Vietnam have already lost their natural vegetation and the soils areexposed to intense soil erosion. In the upland areas several cultivation practices such as slopinggardens, rice terraces, intercropping and agro-forestry have been identified which have high potentialfor economic return and sustainability of soil resources.
3
Figure 3. Soils of northern Vietnam.
Table 1. Agricultural land use in Vietnam as recorded in 2002.(Source: General Statistics Office, 2003).
Total Land Agricultural land Forestry land Specially used land Homestead land
Region (‘000 ha)
Red river delta 1480 855 122 239 92Northeast 6533 916 2840 217 61Northwest 3564 414 1145 61 16North center coast 5151 736 2300 244 54South center coast 3307 549 1199 217 34Central highlands 5448 1288 3016 148 35Southeast 3474 1687 1068 254 61Mekong river delta 3973 2962 361 237 100Total country 32930 9407 12051 1616 451
Soils accumulate iron and aluminum to form laterite. Mineralization is rapid, and organic substancesquickly break down, resulting in low humus content. Intensive surface cultivation and leachingprocesses make the soils very acidic and poor in nutrients. Nitrogen, phosphate and cations are easilydissolved or carried away to such an extent that these soils cannot be sustainably cultivated for longand become degraded. In extreme cases of soil erosion, the hardpan of laterite nodules is exposed.
Land use Systems in Vietnam
According to General Statistics Office (2003), the agricultural land is 9.4 million ha and forestry landcover is 12.05 million ha. Most of the agricultural land is under annual crops and a small part allocatedto perennial crops (Table 1).
4
Long-term yields of crops depend on soil type, slope, soil depth, soil fertility, environmentalconditions and farm management in each region. Some annual crops are planted on sloping landsbut the grain yields are normally less than those obtained on the lowlands due to limitation ofwater, soil, farm management practice and socioeconomic factors. In general, annual crops aregrown in the lowlands and intercropping systems of annual and perennials in the uplands. Theperennial crops are situated on uplands and hills. Most of the sloping lands are used for forestry,horticulture and agriculture and a large area in Vietnam remains unused. The uplands are notsuitable for rice, therefore, perennial, industrial and forest trees have existed under rainfedconditions. However, in the uplands paddy rice is also planted in the valleys where irrigationfacilities exist.
Province-wise Area, Production and Productivity of Crops in northernVietnam
Northern Vietnam comprises of 25 provinces (excluding north central coast) and most of themhave area under soybean, peanut and maize. There has been a general increase in area, productionand productivity of soybean in northern Vietnam since 1994-95. The largest soybean area is in SonLa in the northwest and Ha Tay in the red river-delta. The area under soybean in these provincesincreased rapidly from 6000–8000 ha in 1994–1995 to 10000–11000 ha in 2001–2003.Productivity of soybean was 1.25–1.5 t ha-1 in Thai Binh and 0.75–1.0 t ha-1 in Ha Tay in 1994–1995,which increased to 2.0–2.05 t ha-1 in Thai Binh and 1.31–1.37 t ha-1 in Ha Tay in 2001–2003. Theseprovinces are located in the red river delta, where lands have irrigation system and good farmmanagement practices are followed compared to Lao Cai, Ha Giang and Cao Bang mountainousprovinces (Fig. 4).
Cultivation of peanuts also increased in most of the provinces, except Lao Cai, Yen Bai, Cao Bangand Hai Phong. Area in Phu Tho province has increased from 4000–6000 ha in 1994–1995 to6000–8500 ha in 2001–2003 (Fig. 5). The productivity of peanuts over the years has increased inmost of the provinces, except Son La and Cao Bang. It increased from 1.0–1.25 t ha-1 in 1994–1995 to 2.5–3.5 t ha-1 in 2001–2003 in Nam Dinh, Hung Yen and Hai Phong provinces (Fig. 5).Since 1999, polythene mulch technology for soil moisture conservation and increasing soiltemperature during germination and early plant growth stage, and integrated pest managementpractices were applied in all the provinces of red river delta. This has improved the productivityof peanut by 30 to 70% as compared to absolutely no mulching and traditional practice (Chinhand Thang 2000; Chinh et al. 2002).
Maize is the main crop in the mountainous area of northern Vietnam. Maize area hasincreased in some provinces, particularly in Lao Cai, Son La and Ha Giang (Fig. 6). Theseprovinces are located in northeast and northwest of Vietnam, and cover large upland areas.The maize area in these provinces increased from 20000 ha–30000 ha in 1994–1995 to over40000 ha in 2001–2003. The productivity has rapidly increased in parts of red river deltasuch as Ha Tay, Hung Yen, Thai Binh, Hai Duong and Hai Phong provinces from 2.5–3.0 t ha-
1 in 1994–1995 to 3.5–4.5 t ha-1 in 2001–2003. In the northeast region, which includes TuyenQuang and Lang Son provinces, productivity increased from 2.0–2.5 t ha-1 in 1994–1995 to3.5–4.5 t ha-1 in 2001–2003 (Fig. 6). Most of these provinces are growing hybrid maizecultivars and have applied improved crop management practices promoted by Vietnam MaizeResearch Institute since 1998.
5
Figure 4. Province-wise changes in area, production and productivity of soybean in northern Vietnam.
6
Figure 5. Province-wise changes in area, production and productivity of peanut in northern Vietnam.
7
Figure 6. Province-wise changes in area, production and productivity of maize in northern Vietnam.
8
Crop Production in Six Selected Provinces of northern VietnamThe six provinces selected for the study were Phu Tho, Vinh Phuc, Ha Tay, Hoa Binh, Ha Nam and NinhBinh. The geographical location of provinces and the districts in each province are given in Figure 7.
Ha Tay, Ha Nam, Ninh Binh and Vinh Phuc provinces are located in the Red River Delta region. Theseprovinces have both upland and lowland area sown to annual and perennial crops. The upland districtsin the Ha Tay province are Son Tay, Phuc Tho and Ba Vi, and the other districts mostly have lowland
Figure 7. Districts in six selected provinces of northern Vietnam.
9
area. Out of six districts of Ha Nam province, Kim Bang, Ly Nhan and Thanh Liem mostly haverainfed area. Most of the area in the Ninh Binh province is rainfed. Major land use in Ninh Binh isforestry (20,000 ha) and it ranks second after Vinh Phuc province (30,000 ha). After forestry, in mostof the areas perennial and industrial crops are grown and a small area is given to growing food crops.
Phu Tho province has now been divided into Phu Tho and Vinh Phuc provinces. Vinh Phuc is locatedin the Red River Delta with seven districts. Out of the seven districts Vinh Yen and Me Linh havelowland area, and other districts mostly have uplands with no irrigation system including the TamDuong district where participatory watershed management project is being conducted. Phu Thoprovince is situated in the northeast region having twelve districts. All the districts are rainfed withimpoverished soils and low economic efficiency of cropping systems due to many constraints such aslack of knowledge about cropping practices, poor socioeconomic conditions, marketing and transportlimitation. Major crops are cassava, tea, maize, sweet potato and peanut.
Hoa Binh is in the north-west region. It covers eleven rainfed districts, in which Kim Boi is 70 kmaway from Ha Noi, where currently the watershed project is operational since 1999. Major crops ofthe province are maize, cassava, watermelon and tea.
Climate and Soils
Annual rainfall in the six provinces ranges from 1580 to 1930 mm. The maximum temperatures range from32.7 to 33.6 °C, and the minimum temperatures from 14.0 to 14.9°C (Table 2). Both maximum andminimum temperatures have the lowest value in January and December. The temperatures start risingtowards end of January and reach maximum value in June and July. Then they start falling again and reach thelowest value in January (Fig. 8). These data show that major variation in crop productivity in these provinceswould be caused by amount and distribution of rainfall. In most provinces rainfall exceeds potential evapo-transpiration from March to October (8 months) indicating the positive water balance. Most of the sites havehigh potential harvest excess rainfall in surface ponds or for recharging the ground water. All the soils atbenchmark sites are ferralitic, red-yellow in color and soil depth is more than 80 cm (Table 3).
Table 2. Geographical location and climate of the benchmark sites in northern Vietnam.
Latitude Longitude Annual Annual average Annual average WeatherLocation (N) (E) rainfall (mm) max.temp.(°C) min.temp.(°C) years
Vinh Yen, Vinh Phuc 21.17 105.35 1580 33.2 14.5 70–99Ha Nam 20.32 105.60 1930 32.8 14.0 60–97Ninh Binh 20.25 105.99 1820 32.7 14.6 60–03Phu Ho, Phu Tho 21.25 105.16 1680 32.9 14.0 70–03Son Tay, Ha Tay 21.08 105.25 1770 33.1 14.2 62–03Chi Ne, Hoa Binh 20.30 105.50 1760 33.6 14.9 94–03
Table 3. Soils of the benchmark sites in northern Vietnam.(Source: Siem and Phien, 1999).
Location Soil type Soil series Soil color
Vinh Phuc Ferralitic Tam Duong Red-yellowHa Nam Ferralitic Duy Tien Red-yellowNinh Binh Ferralitic Ninh Binh Red-yellowPhu Tho Ferralitic Phu Ho Red-yellowHa Tay Ferralitic Ha Tay Red-yellowHoa Binh Ferralitic Kim Boi Red-yellow
10
Figure 8. Monthly average rainfall (mm), potential evapo-transpiration (mm), maximum and minimumtemperatures (oC) and solar radiation (MJ m-2) of sites located in the six provinces of northern Vietnam.
11
Figure 9. Land use in the six benchmark locations in northern Vietnam.(Source: General Statistics Office, 2003).
Major Crops
The major crops grown in six benchmark locations are rice, maize, peanut, sugarcane, cassava andsoybean (Fig. 9). Of these rice is the dominant crop in all the locations, whereas maize area is rankedsecond. Legume crops are new and their area is less when compared to other crops. Most of cropproduce is consumed by ethnic minorities in the watershed. Rice, peanut and soybean (tofu) arepopular in the family’s meal and help in meeting the protein and vitamin requirements for poorfarmers, who have low income. Cassava and maize are considered as staple food and also used forfeeding domesticated animals in the mountainous area. It also becomes main food for human beingswhen rice harvest is lost.
12
Figure 10. Major rainfed cropping systems at six benchmark sites.
Maize Soybean
Sugarcane or cassava
Peanut Maize
Maize Rainfed rice
Maize Mungbean
Watermelon Peanut
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Prominent Cropping Systems
The rotations of maize-soybean, peanut-maize, rainfed rice-maize and soybean-mung bean; and mono-cultures of sugarcane, cassava or tea are the main cropping systems practiced in the watershed area ofsix provinces, where legumes and maize appear in most of the crop rotations. Thus maize and legumesplay an important role in the existing rainfed farming systems. The farmers normally cultivate twomain crops under rainfed situations. Depending upon the amount of rainfall received, the first crop issown in February to March and harvested by the end of May or during June. The second crop is sownin July and harvested in November (Fig.10). Cassava and sugarcane have long-duration and usuallysown in January to February and harvested in November. Tea is a perennial crop planted in March toAugust and harvested throughout the year.
Area Production and Productivity of Crops in the Provinces
In the six provinces maize is the main rainfed crop. However, legumes are important part of croppingsystem. Soybean area is small in all the six provinces. The highest area (>3000 ha) is in Ha Tay, whileHa Nam province achieved the highest productivity of about 1.6 t ha-1 (Fig.11 and 12). During theperiod 1995–1997, soybean was mostly grown in twelve districts out of sixty districts of six provinces.In 2001–2003 it expanded to sixteen districts. In Phu Xuyen district of Ha Tay province and in VinhYen district of Vinh Phuc province the area under the crop increased from 1200–1600 ha in1995–1997 to 2000–2400 ha in 2001–2003. This increase in area occurred because of the
13
introduction of new high-yielding soybean cultivars (such as AK 06, DT 84 and DT 12) and goodfarmer practice (minimum tillage) since 1999. Soybean is grown in the winter season with irrigationafter rice harvest. Soybean productivity in the districts ranged from 0.4–0.8 to 2.0–2.4 t ha-1.
Peanut is also grown in all the benchmark sites under rainfed condition as it is drought tolerant.However, its productivity is low and ranges from 1.1 to 2.2 t ha-1. Currently the major peanutproducing provinces are Ha Tay, Ninh Binh and Phu To (Fig. 13 and 14). The increase in production inthese provinces occurred both due to increase in area and increase in productivity. No major increasein production occurred in Vinh Phuc, Ha Nam and Hoa Binh provinces since 1995, although largeimprovement in productivity occurred in Ha Nam. Currently Ha Nam and Ninh Binh haveproductivity levels exceeding 2.0 t ha-1. Peanut was cultivated in twelve districts in 1998–2000 and itexpanded to thirteen districts during 2001–2003. In the Phu Tho province, peanut area expandedfrom none in 1995–1997 to 1.8–2.4 thousand ha in 2001–2003, mostly in the Ha Hoa, Thanh Ba,Cam Khe, Yen Lap and Thanh Son districts. In the Ninh Binh province, the area increased from24,000 in 1995 to 30,000 ha in 2003 in the Nho Quan district. Peanut productivity has increased in all
Figure 11. Area, production and productivity of soybean in different provinces in northern Vietnam.
14
Figure 12. District-wise changes in area, production and productivity of soybean in selected provinces ofnorthern Vietnam.
the six benchmark locations, which ranged from 1.8 to 2.2 t ha-1 during 2001–2003. In the Phu Xuyenand Thuong Tin districts of Ha Tay province, peanut productivity increased from 1.0–1.4 t ha-1 during1995–1997 to 2.2–2.6 t ha-1 during 2001–2003 because of the adoption of improved peanut cultivars(MD7, L14 and L18) and polythene mulching technology.
Maize is a common crop in almost all the districts of the six provinces and since 1995, maizeproductivity has increased in all the six provinces (Figs. 15 and 16). The productivity levels in 2003ranged from 2.7 to 4.1 t ha-1 across provinces. The highest increase being in Ha Tay (4.1 t ha-1), wheremaize is partly grown on low lands with some irrigation. Maize area is more in Vinh Phuc, Ha Tay andHoa Binh followed by Phu Tho, Ha Nam and Ninh Binh. The increase in total production in VinhPhuc, Ha Tay, Ha Nam and Ninh Binh provinces has been primarily due to increase in productivitythan increase in area. Whereas, in Phu Tho and Hoa Binh the production increased due to increase inboth area and productivity. Availability of new hybrid cultivars and improved farm practices have beenthe reason for increased production and productivity of maize in the six provinces.
In general, the productivity of maize, peanut and soybean in benchmark watersheds is low comparedto the potential yield of the cultivars. The reasons for low productivity could be low adoption of
15
Figure 13. Area, production and productivity of peanut in different provinces in northern Vietnam.
16
Figure 14. District-wise changes in area, production and productivity of peanut in different provinces ofnorthern Vietnam.
improved management practices, poor socioeconomic condition of farmers, degraded soils andadverse climatic conditions. Yield gap analysis of three crops could help in identifying the majorconstraints to higher yields and a scope for yield improvement.
Potential Yields and Yield Gaps of Major CropsPotential yield is defined as the maximum possible yield of a crop obtained under optimummanagement. Under irrigated conditions, radiation and temperature during the season determine theupper limit of the potential yield under optimum management. Whereas under rainfed conditions,potential yields are primarily limited by water availability and considered as water-limited potentialyields. Maximum experimental yields obtained at research stations, under irrigated or rainfedsituation, are usually considered as the potential yields for estimating the yield gaps.
Traditional Method of Yield Gap AnalysisIn the traditional method, experiment station yields along with the average yield of at least 10 on-farmtrials, and district average yield were used for calculating yield gaps. The on-farm trials were
17
Figure 15. Area, production and productivity of maize in different provinces in northern Vietnam.
18
Figure 16. District-wise changes in area, production and productivity of maize in different provinces innorthern Vietnam.
conducted both with improved technology (integrated management) and traditional managementpractices. Total yield gap was expressed as the difference in yield between experimental station yieldand the district average yield. This was further partitioned into yield gap I and yield gap II. Yield gapI was defined as the difference in yield between the experiment station maximum yield and the on-farm trial yield under improved management, whereas yield gap II was the difference in yield betweenthe on-farm trial yield under improved management and the district average yield.
Experimental station yields and yield gap of soybean: The soybean experiments were mostlyconducted in spring with some irrigation and in summer as rainfed, while in lowlands it is mostlyplanted in winter after rice harvest, with irrigation. Large differences exist in soybean yield betweenrainfed and irrigated eco-system. Average potential yield (experimental) under rainfed conditionranged from 1720 to 2180 kg ha-1 (Table 4). Total yield gap (between experimental station yield anddistrict average) soybean is quite large, ranging from 510 to 1260 kg ha-1. Maximum total yield gap wasobserved at Tan Lac, while the minimum was at Kim Boi in Hoa Binh province. Yield gap I (betweenthe experimental station yield and on-farm trial) was quite narrow ranging from 180 to 420 kg ha-1 forthe locations. The yield gap II ranged from 180 to 980 kg ha-1.
Experimental yield of irrigated soybean during winter season ranged from 2310 to 2620 kg ha-1 acrossthe provinces. When compared with the district average yields, the total yield gap ranged from 1010
19
Table 4. Experimental station and on-farm yield and the yield gap of rainfed soybean atbenchmark locations in northern Vietnam.
Expt. stn.On-farm yield
DistrictYield gap
yield Imp* Trad** yield I II Total
Province District Period Season (kg ha-1)
Vinh Phuc Tam Duong 98–04 Summer 1810 1580 1170 1030 260 810 780 Vinh Tuong 98–04 Summer 2040 1790 1330 1160 230 610 880Hoa Binh Kim Boi 99–03 Summer 1990 1680 1560 1350 210 330 540 Tan Lac 99–03 Summer 2010 1730 — 750 280 980 1260Ninh Binh Nho Quan 96–99 Summer 2050 1630 1350 920 420 710 1130 Yen Khanh 96–99 Summer 2180 1820 1720 1640 360 180 530
Mean 2000 1710 1430 1140 290 600 860
Hoa Binh Kim Boi 99-03 Spring 1860 1620 1470 1350 240 270 510 Tan Lac 99-03 Spring 1720 1540 1330 750 180 790 970
Mean 1790 1580 1400 1050 210 530 740
*Imp = Improved **Trad = Traditional
Table 5. Experimental station and on-farm yield and yield gap of irrigated soybean at benchmarklocations in northern Vietnam.
Expt. stn.On-farm yield
DistrictYield gap
yield Imp* Trad** yield I II Total
Province District Period Season (kg ha-1)
Ha Tay Ung Hoa 98–01 Winter 2510 2310 1620 1140 190 1170 1360 Phu Xuyen 98–01 Winter 2310 2030 1530 1230 290 800 1080 Thuong Tin 98–01 Winter 2330 1940 1620 1060 390 880 1270Ha Nam Duy Tien 96–99 Winter 2480 2180 1560 1470 300 710 1010 Binh Luc 96–99 Winter 2620 2380 1590 1470 250 910 1160
Mean 2450 2170 1580 1270 280 890 1180
*Imp = Improved **Trad = Traditional
to 1360 kg ha-1. The minimum yield gap was observed at Duy Tien, while Ung Hoa has the maximumyield gap. The yield gaps were larger under the irrigated conditions than under rainfed conditionsbecause of higher potential yields with irrigation. These results indicate the importance ofsupplemental irrigation with water harvesting to bridge the yield gaps.
Experimental station yields and yield gap of peanut: Peanut is an important legume crop and is betteradapted to rainfed conditions. However, the pod yield varies among locations due to differences insoil, climate, cultivars and management practices. In the spring season, experimental yield (cultivarL14) of rainfed locations ranged from 2200 to 3740 kg ha-1. The maximum pod yield was observed atKim Boi, while minimum yield was recorded at Tam Duong (Table 6). Total yield gap ranged from1050 to 2550 kg ha-1, the largest at Kim Boi and the smallest at Son Tay district. Yield gap II rangedfrom 460 to 1810 kg ha-1. In the autumn season, the experimental yields ranged from 1910 to 2300 kgha-1 and the yield gap from 710 to 1060 kg ha-1.
20
Table 6. Experimental station and on-farm yield and yield gap of rainfed peanut at benchmarklocations in northern Vietnam.
Expt. stn.On-farm yield
DistrictYield gap
yield Imp* Trad** yield I II Total
Province District Period Season (kg ha-1)
Ha Tay Son Tay 99–02 Spring 2430 1980 1720 1380 440 600 1050 Ba Vi 99–02 Spring 2580 2190 1700 1070 390 490 1510Ha Nam Binh Luc 99–02 Spring 3370 2850 2350 1620 520 1230 1740 Kim Bang 99–02 Spring 3300 2920 2520 2110 380 810 1190Ninh Binh Nho Quan 00–03 Spring 2550 2020 1680 1210 530 1120 1350Vinh Phuc Tam Duong 98-00 Spring 2200 1780 1460 940 420 840 1260 Vinh Tuong 98-00 Spring 2570 1960 1660 1500 610 460 1070
Hoa Binh Kim Boi 97 Spring 3740 3000 2190 1190 740 1810 2550 00-02 Spring 3120 2440 1960 1300 720 1140 1810 Tan Lac 03 Spring 2490 2000 1770 940 490 1060 1550
Mean 2830 2310 1900 1330 520 960 1510
Vinh Phuc Tam Duong 03 Autumn 2300 2080 1800 - 220 - -Hoa Binh Tan Lac 03 Autumn 2000 1710 1500 940 290 770 1,060
Tan Lac 99 Autumn 1910 1600 1400 1200 310 400 710
Mean 2070 1800 1570 1070 270 590 890
*Imp = Improved **Trad = Traditional
The yield gap of irrigated peanut for some of the locations was also calculated. The largest totalyield gap was observed at Chuong My, Ha Tay and the smallest at Duy Tien, representing 1780 kgha-1 and 810 kg ha-1, respectively (Table 7). It was observed that yield gap (II) and total yield gapvaried among locations.
Table 7. Experimental station and on-farm yield and yield gap of irrigated peanut at benchmarklocations in northern Vietnam.
Expt. stn.On-farm yield
DistrictYield gap
yield Imp* Trad** yield I II Total
Province District Period Season (kg ha-1)
Ha Nam Duy Tien 99–02 Spring 3200 2800 2400 1950 400 850 1250 00–02 Spring 3380 3040 2670 2570 350 470 810Ha Tay Chuong My 99–02 Spring 3250 2840 2600 1500 410 1360 1780Ninh Binh Yen Khanh 00–03 Spring 3670 3110 2740 2500 550 1240 1170
Mean 3380 2950 2600 2120 430 980 1250
*Imp = Improved **Trad = Traditional
Simulation Approach of Yield Gap AnalysisSimulation of rainfed potential yields: Using a crop growth simulation model for determiningpotential yields requires inputs of weather, soil and cultivar-specific parameters (genetic coefficients)and crop management data. The crop growth model must be calibrated for the soil and cultivar-specific parameters through several model iterations such that the simulated results match the
21
observed data on phenology, crop growth, yield and soil water dynamics. Once the model is validatedit can be used to simulate variations in water-limited potential yields caused by weather variabilityusing historical records of weather. Genetic coefficients of the crop cultivars were determinedaccording to Hunt’s (1988) approach. This was accomplished iteratively by executing the model withapproximate coefficients, comparing model output with actual data and then re-adjusting thecoefficients and the repeating process until acceptable fits are obtained. Genetic coefficients werecalculated from the field data using GENCALC, a utility module embedded in DSSAT v3.5(Hoogenboom et al. 1999). All the genetic coefficients of maize (Var. VN 10), peanut (Var. L 14) andsoybean (Var. AK 06) were estimated by using phenology and growth data from experimentsconducted from 2000 to 2003 at Thanh Ha watershed.
Soil file for each watershed sites was created using soil physical and chemical proprieties data for thewatershed area and the soil profile utility program available in DSSAT v3.5 software. The soilparameters were further modified to make them more specific to the experiment site (Naab et al.2004). This was accomplished by changing the soil parameters and comparing the model output onsoil water dynamics with the observed data until both matched. First the upper (DUL) and lowerlimits (LL), and saturation limits (SAT) of the soil layers were set. Then, the runoff and drainagecoefficients and root-distribution coefficients were adjusted such that the soil water changes for eachlayer matched the observed data. All parameters were modified through iterations of the model run tofit between observed and simulated data for three crop experiments such as maize (spring 2000,summer 2000 and spring 2001); soybean (spring 2000, 2001 and 2002); and peanut (spring 2000,2001 and 2002). Physical parameters of the soil profiles of six benchmark sites used for simulation isgiven in Table 8. All experiment files, containing crop, soil, climate and management data wereentered in soybean, peanut and maize model directories. Multi-year seasonal analysis was used todetermine potential yields for the six locations. All results were used to analyze yield gaps for thethree crops in benchmark locations in northern Vietnam.
Simulated potential yield and yield gap of soybean: For simulating the potential yield of soybean,sowing window was setup for different seasons. Sowing window was 15–30 April for all locations,except for Ninh Binh and Phu Tho provinces because of late rainfall in spring season. In the model,sowing was considered to have taken place when at least 40% of extractable soil moisture waspresented in the top 30 cm soil layer. The sowing window for summer sowing was 30 June to 15 July.Simulations were made for the six locations, using long-term weather data records available (Table 9).
Means of simulated yields were compared with the means of rainfed experimental and province yieldsto calculate yield gaps. Total yield gap for rainfed soybean ranged from 610 to 1110 kg ha-1 in both the
Table 8. Soil depth, saturation limit (SAT), drained upper limit (DUL), lower limit (LL),extractable water capacity (EXTW), USDA runoff curve number (CN2) and drainage coefficient(SLDR) of the soil profiles used for simulation.
Location Depth (cm) SAT (mm) DUL (mm) LL (mm) EXTW (mm) CN2 SLDR
Vinh Phuc 100 350 211 195 116 68 0.70Ha Nam 120 535 406 200 206 76 0.60Ninh Binh 150 572 512 351 161 76 0.60Phu Tho 100 436 411 292 122 80 0.60Ha Tay 100 478 403 230 174 80 0.60Hoa Binh 120 441 345 197 149 76 0.70
22
seasons (Table 10). The largest yield gap between potential yield and province yield of rainfed soybeanwas observed at Ha Tay and the lowest at Ha Nam provinces. The yield gaps were large in summer ascompared to those in spring; hence, it is seen that there is a high potential for increasing yield forsoybean in summer season than in the spring.
Table 9. Sowing window and simulation date for soybean during spring and summer seasons usedin seasonal analysis.
Sowing window Simulation date
Location Spring Summer Spring Summer Years
Vinh Phuc 15–30 Apr 30 Jun–15 Jul 01 Feb 30 Apr 28Ha Nam 15–30 Apr 30 Jun–15 Jul 01 Feb 30 Apr 28Ninh Binh 20 Apr–5 May 30 Jun–15 Jul 01 Feb 30 Apr 28Phu Tho 20 Apr–5 May 30 Jun–15 Jul 01 Feb 30 Apr 28Ha Tay 15–30 Apr 30 Jun–15 Jul 01 Feb 30 Apr 28Hoa Binh 15–30 Apr 30 Jun–15 Jul 01 Feb 30 Apr 10
Simulated soybean yield showed a strong linear relationship with seasonal rainfall (Y = 0.78 x + 1315.7;and R2 = 0.67). In which Y = simulated soybean yield (kg ha-1) and x = rainfall (mm) during cropgrowth season. This implies that the production potential of soybean increases as the seasonal rainfallincreases. (Fig.17). Surface runoff and deep drainage from the soil profile were also strongly correlatedwith seasonal rainfall (for runoff: Y = 0.38x –144.81 and R2 = 0.74, and for deep drainage: Y = 0.29 x– 50.866 and R2 = 0.54). In which Y = simulated runoff or deep drainage (mm) and x = rainfall (mm)
Table 10. Simulated potential yield, experimental station yield, provincial average yield and yieldgap of rainfed soybean in the spring and summer seasons at benchmark locations in northernVietnam.
Simulated Expt. ProvinceYield gap
yield yield yield I II Total
Location (kg ha-1)
Spring seasonVinh Phuc 1950 1750 1300 200 450 650Ha Nam 2240 1860 1630 380 230 610Ninh Binh 1810 1740 1180 70 560 630Phu Tho 1760 1600 - 160Ha Tay 2150 1900 1320 250 580 830Hoa Binh 2110 1790 - 320
Mean 2000 1770 1360 230 460 680
Summer seasonVinh Phuc 2330 1920 1300 410 630 1030Ha Nam 2480 1860 1630 620 230 850Ninh Binh 2230 2110 1180 110 930 1050Phu Tho 2160 1790 - 370Ha Tay 2430 2140 1320 290 820 1110Hoa Binh 2440 1950 - 490
Mean 2350 1960 1360 380 650 1010
23
Figure 17. Relationship of soybean yield, surface runoff and deep drainage with seasonal rainfall during springand summer seasons at six benchmark locations.
during crop growth season. These results indicate the potential for runoff water harvesting andgroundwater recharging at six benchmark locations as the amount of rainfall increases (Fig. 17).
Simulated potential yield and yield gap of peanut: The spring season for peanut starts earlier ascompared to soybean and maize, as peanut is more drought tolerant during initial stages of its growthunder rainfed condition. The sowing window for spring season was kept between 15 March and 15 Apriland simulation started 2 January. Autumn-winter sowing window was kept between 15 August to 15September after soybean and maize and simulation started on 29 June for all the locations (Table 11).
24
Mean simulated yields were compared to rainfed experimental and province yields for each locationto calculate yield gaps. Because of high potential yield due to more favorable climate for peanutgrowth, the yield gap was larger in spring season (Table 12). These results support the earlier finding ofReddy (1988) that peanut crop yields are higher when temperatures are between 20–30°C andrainfall is well distributed. Total yield gaps observed at Hoa Binh (3,050 kg ha-1), Ha Tay (3,000 ha-1)and Vinh Phuc (2,700 ha-1) were larger compared to other sites during the spring season.
The simulated yield of peanut in autumn-winter was less compared to the yield in spring due to variabilityin the amount and distribution of rainfall. If autumn-winter season crop is sown between 15 August and 15September, then flowering takes place between 25 September and 25 October. During this period lowradiation decreases flowering, pegging, pod numbers, pod filling and maturity of crop (Reddy 1998).
Table 11. Simulation dates and sowing windows for six watershed sites used for seasonal analysis ofrainfed peanut.
Sowing window Simulation date
Location Spring Autumn-winter Spring Autumn/ winter Weather years
Vinh Phuc 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 28Ha Nam 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 28Ninh Binh 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 28Phu Tho 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 28Ha Tay 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 28Hoa Binh 15 Mar–15 Apr 15 Aug–15 Sep 2 Jan 29 Jun 10
Table 12. Simulated potential, experimental and province average pod yield and yield gap of rainfedpeanut in the spring and autumn-winter seasons at benchmark locations in northern Vietnam.
Yield gap
Simulated yield Exptl. yield Province yield I II Total
Location (kg ha-1)
Spring seasonVinh Phuc 3900 2380 1200 1500 1180 2700Ha Nam 4700 3330 2200 1360 1130 2500Ninh Binh 3740 2550 1710 1190 840 2030Phu Tho 3870 3400 1270 470 2130 2600Ha Tay 4560 3200 1560 1360 1640 3000Hoa Binh 4230 3200 1180 1030 2020 3050
Mean 4170 3010 1520 1150 1490 2650
Autumn-winter seasonVinh Phuc 3270 2300 1200 970 1100 2070Ha Nam 3920 2780 2200 1140 580 1720Ninh Binh 3430 2700 1710 730 990 1720Phu Tho 2910 - 1270 1640Ha Tay 3880 2500 1560 1379 940 2320Hoa Binh 3760 2800 1180 960 1620 2580
Mean 3530 2620 1520 1040 1050 2010
25
Pod yields were significantly correlated with the amount of rainfall received during spring andautumn-winter seasons (spring season: Y= 3.17 X + 1935.81, R2 = 0.35; autumn winter season:Y= 2.78 X + 1102.69, R2 = 0.48). However, the pod yields were low during the autumn-winterseason because of the limitation imposed by the availability of solar radiation and low temperatures(Fig.18). The relationships of surface runoff and drainage with seasonal rainfall were strong (forrunoff: Y = 0.41x – 143.36; R2 = 0.82 and for deep drainage: Y = 0.31x - 91.24; R2 = 0.69).
Figure 18. Relationship of peanut yield, surface runoff and deep drainage with seasonal rainfall during springand summer seasons at six benchmark locations.
26
Simulated potential yield and yield gap of maize: Maize is normally sown in spring and summer in therainfed area of northern Vietnam. Sowing window for spring season was 1 to 15 April and for thesummer season it was 1 to 15 June. The crop was sown whenever the soil water in the top 30 cm soildepth reached at least 40% of available water capacity. Seasonal analysis for maize yields was done for28 years for the five locations (Vinh Phuc, Ha Nam, Ninh Binh, Ha Tay and Phu Tho) and 10 years forthe Hoa Binh (Table 13).
Yield gap was calculated between simulated and province yields. It ranged from 1030 kg ha-1 (19.7%)in Ha Tay in the spring season to 2650 kg ha-1 (49.9%) in Hoa Binh in summer season. Simulated yieldsin summer season were more than those in spring season, hence total yield gap is larger in summerseason (Table 14).
Relationship between grain yield and rainfall was very strong (Y= 0.69 X + 4419.3; R2= 0.60).Similarly surface runoff and deep drainage were also very strongly correlated with seasonal rainfall(for runoff: Y = 0.38 x – 137.2; R2 = 0.78; for deep drainage: Y = 0.25 x – 46.5, R2 = 0.62) (Fig.19).
Table 14. Simulated potential and province average yield and yield gap of rainfed maize in thespring and summer seasons at benchmark locations in northern Vietnam.
Simulated yield Province yield Yield gap
Location (kg ha-1) Yield gap(%)
Spring seasonVinh Phuc 4890 3290 1600 33Ha Nam 5430 3520 1910 35Ninh Binh 4800 3360 1440 30Phu Tho 4980 3240 1740 35Ha Tay 5210 4180 1030 20Hoa Binh 4850 2660 2190 45
Mean 5030 3380 1650 33
Summer seasonVinh Phuc 5330 3290 2040 38Ha Nam 5570 3520 2050 37Ninh Binh 5310 3360 1950 37Phu Tho 5250 3240 2010 38Ha Tay 5420 4180 1240 23Hoa Binh 5310 2660 2650 50
Mean 5370 3380 1990 37
Table 13. Sowing window and simulation date for rainfed maize in the seasonal analysis.
Sowing window Simulation date
Location Spring Summer Spring Summer Weather years
Vinh Phuc 01–15 Apr 15–30 Jun 1 Feb 15 Apr 28Ha Nam 01–15 Apr 15–30 Jun 1 Feb 15 Apr 28Ninh Binh 01–15 Apr 15– 30 Jun 1 Feb 15 Apr 28Phu Tho 01–15 Apr 15–30 Jun 1 Feb 15 Apr 28Ha Tay 01–15 Apr 15–30 Jun 1 Feb 15 Apr 28Hoa Binh 01–15 Apr 15–30 Jun 1 Feb 15 Apr 10
27
Constraints and Opportunities for Bridging the Yield GapsThe main constraints for low yields of rainfed crops in northern Vietnam are undulating topography,poor soil fertility, drought and less adoption of improved soil, water, nutrient, crop and pestmanagement practices leading to inefficient use of natural resources such as rainfall (Wani 2003).
Socioeconomic factors (socioeconomic status, farmer’s traditions and knowledge, family size,household income/expenses/investment) and institutional/policy factors such as government policy,
Figure 19. Relationship of maize yield, surface runoff and deep drainage with seasonal rainfall during springand summer seasons at six benchmark locations.
28
product prices, credit, input supply and market, land tenure, linkages factors that consist of thecompetence and facilities of extension staff; integration among research, development and extension;farmers’ resistance to new technology; knowledge and skills; weak linkages among public, private andnon-governmental extension staff also contribute to the problem significantly.
The results from the current study revealed that quite large yield gaps exist between the potential yieldsand current yields of maize, peanut and soybean in six provinces of northern Vietnam. This vast potentialof the rainfed areas of northern Vietnam need to be harnessed through large-scale adoption of improvedsoil, water, crop and pest management options available. Traditionally much emphasis is put ondeveloping new cultivars, however, the findings from the current study and a number of earlier studiessuggest that without appropriate soil, water and nutrient management options the true potential ofimproved cultivars cannot be harnessed. Availability of soil moisture during the crop growth period isvery critical as evident from the significant and strong relationship between rainfall and crop yields.
There is also a strong relationship between rainfall, runoff and deep drainage, highlighting the urgentneed to develop appropriate rainwater management strategies in northern Vietnam to minimize landdegradation and to increase productivity of rainfed crops for achieving food security and improvedlivelihoods. Integrated watershed management approach, which is evaluated by VASI and ICRISAT atbenchmark watersheds in Hoa Binh and Vinh Phuc provinces have shown the large potential forreducing land degradation and increasing productivity of crops by adopting integrated genetic andnatural resource management (IGNRM) approach (Wani 2003).
A yield gap reduction can be seen as the local solution to a global problem. It can lead to increasedproduction with the additional incentive of cost reduction, poverty alleviation, social justice andequity and also minimize land degradation while improving environmental quality. While no majorbreakthrough is expected immediately, reducing the yield gap alone could supply 20 to 60% of theincreased annual food demand by the year 2025 (FAO 2004).
ReferencesChinh NT and Thang NV. 2000. New technology for peanut growing in Vietnam. Annual Report 6/2000, VASI,Vietnam.
Chinh NT, Long TD, Tam HM and Thang NV. 2002. Research and development of polythene mulch techniquefor groundnut production in Northern Vietnam. Annual Report 2002, VASI. Agricultural Publishing House,pp.149–155.
FAO Trade (1995–1999). Statistics of agriculture, forestry and aquaculture by year 2000–2003.
FAO. 2004. Fact sheet No 5 on International year of rice (www.rice2004.org).
General Statistics Office. 1996. Statistical Year book, Statistical Publishing House, Ha Noi, Vietnam. Pages 334.
General Statistics Office. 2003. Statistical Year book, Statistical Publishing House, Ha Noi, Vietnam. Pages 698.
Hoogenboom G, Wilkens PW, Thornton PK, Jones JW, Hunt LA and Imamura DT. 1999. Decision supportsystem for agrotechnology transfer v3.5. In Hoogenboom G, Wilkens PW and Tsuji GY. (eds.). DSSAT version3, vol. 4. University of Hawaii, Honolulu, pp. 1–36.
Hunt LA. 1988. IBSNAT’s genetic coefficients: Coping with germplasm diversity. Agrotechnology transfer,newsletter of international (IBSNAT) project and the soil management support services (SMSS). 7: 1–5.
Naab JB, Singh P, Boote KJ, Jones JW and Marfo KO. 2004. Using the CROPGRO- peanut model to quantifyyield gaps of peanut in the Guinean Zone of Ghana. Agronomy Journal, 96: 1231–1242.
29
Reddy PS. 1988. Indian Council of Agricultural Research, New Delhi. 318–324 pp.
Siem NT and Phien T. 1999. Upland soils in Vietnam: Degradation and rehabilitation. Agricultural PublishingHouse, Ha Noi, Vietnam.
Wani SP, Maglinao AR, Ramakrishna A and Rego TJ. (eds.) 2003. Integrated watershed management for landand water conservation and sustainable agricultural production in Asia. Proceedings of the ADB-ICRISAT-IWMI annual project review and planning meeting, Hanoi, Vietnam, 10–14 December 2001. Patancheru502 324, Andhra Pradesh, India: International Crops Research Institute for the Semi-Arid Tropics. 268 p.
30
Appendix IRainfed soybean yield and yield gap (kg ha-1) at benchmark locations in northern Vietnam.
Farmer’s yieldDistrict
Yield gap
Expt.stn. Imp. mgt. Trad. mgt. yield I II Total
Province District Year Season 1 2 3 4 1-2 2-4 1-4
Vinh Phuc Tam Duong 1998 Summer 1700 1563 1300 959 137 604 741 1999 1850 1500 1200 1150 350 350 700 2000 1900 1600 1000 971 300 629 929 2004 1790 1650 1650 1790 Average 1810 1578 1167 1027 262 808 1,040 Vinh Tuong 1998 Summer 2000 1800 1400 1144 200 656 856 1999 1900 1700 1300 1075 200 625 825 2000 2100 1800 1300 1253 300 547 847 2004 2145 1842 Average 2036 1786 1333 1157 233 609 843Hoa Binh Kim Boi 1999 Summer 1820 1700 1523 1190 120 510 630 2000 1900 1650 1563 1170 250 480 730 2001 1823 1689 1598 1170 134 519 653 2002 2000 1659 1500 1710 341 -51 290 2003 1900 1700 1600 1500 200 200 400 Average 1889 1680 1557 1348 209 332 541 Tan Lac 1999 Summer 2200 1800 800 400 1000 2000 1852 1300 630 552 670 2001 1900 1765 720 135 1045 2002 2200 2000 800 200 1200 2003 1890 1800 810 90 990 Average 2008 1733 752 275 981 Ninh Binh Nho Quan 1996 Summer 1800 1540 1100 682 260 858 1118 1997 2200 1600 1400 971 600 629 1229 1998 2000 1654 1354 692 346 962 1308 1999 2200 1723 1540 1333 477 390 867 Average 2050 1629 1349 920 421 710 1131 Yen Khanh 1996 Summer 2100 1800 1560 1413 300 387 687 1997 2100 1700 1600 1332 400 368 768 1998 2300 1823 1700 1895 477 -72 405 1999 2200 1953 2000 1936 247 17 264 Average 2175 1819 1715 1644 356 175 531Hoa Binh Kim Boi 1999 Spring 1900 1659 1523 1190 241 469 710 2000 2200 1750 1654 1170 450 580 1030 2001 1800 1700 1562 1170 100 530 630 2002 1800 1600 1523 1710 200 -110 90 2003 1600 1385 1100 1500 215 -115 100 Average 1860 1619 1472 1348 241 271 512 Tan Lac 1999 Spring 1800 1600 1300 800 200 800 1000 2000 1560 1523 1400 630 37 893 930 2001 1700 1425 1300 720 275 705 980 2002 1821 1624 1400 800 197 824 1021 2003 1720 1542 1268 810 178 732 910 Average 1720 1543 1334 752 177 791 968
31
Appendix IIIrrigated soybean yield and yield gap (kg ha-1) at benchmark locations in northern Vietnam.
Farmer’s yieldDistrict
Yield gap
Expt.stn. Imp. mgt. Trad. mgt. yield I II Total
Province District Year Season 1 2 3 4 1-2 2-4 1-4
Ha Tay Ung Hoa 1998 Winter 2493 2200 1800 1130 293 1070 1363 1999 2354 2300 1700 1010 54 1290 1344 2000 2631 2400 1500 1040 231 1360 1591 2001 2548 2354 1469 1390 194 964 1158 Average 2507 2314 1617 1143 193 1171 1364 Phu Xuyen 1998 Winter 2300 2000 1500 1180 300 820 1120 1999 2350 1950 1650 1210 400 740 1140 2000 2200 1952 1650 1190 248 762 1010 2001 2400 2210 1300 1350 190 860 1050 Average 2313 2028 1525 1233 285 796 1080 Thuong Tin 1998 Winter 2400 2005 1700 1130 395 875 1270 1999 2300 2100 1750 1080 200 1020 1220 2000 2100 1854 1540 1010 246 844 1090 2001 2500 1800 1500 1010 700 790 1490 Average 2325 1940 1623 1058 385 882 1268Ha Nam Duy Tien 1996 Winter 2400 2100 1500 1250 300 850 1150 1997 2400 2000 1453 1320 400 680 1080 1998 2600 2300 1623 1890 300 410 710 1999 2500 2300 1654 1400 200 900 1100 Average 2475 2175 1558 1465 300 710 1010 Binh Luc 1996 2500 2300 1742 1510 200 790 990 1997 2600 2400 1356 1260 200 1140 1340 1998 2700 2300 1569 1620 400 680 1080 1999 2689 2500 1687 1470 189 1030 1219 Average 2622 2375 1589 1465 247 910 1157
32
Appendix IIIRainfed peanut yield and yield gap (kg ha-1) at benchmark locations in northern Vietnam.
Farmer’s yieldDistrict
Yield gap (kg ha-1)
Expt.stn. Imp. mgt. Trad. mgt. yield I II Total
Province District Year Season 1 2 3 4 1-2 2-4 1-4
Ha Tay Son Tay 1999 Spring 2200 1756 1500 1210 444 546 990 2000 2400 1958 1658 1500 442 458 900 2001 2600 1900 1700 1550 700 350 1050 2002 2500 2314 2000 1260 186 1054 1240 Average 2425 1982 1715 1380 443 602 1045 Ba Vi 1999 Spring 2163 1823 1321 800 340 502 521 2000 2346 2000 1752 1000 346 248 752 2001 2900 2500 1800 1080 400 700 720 2002 2900 2415 1912 1380 485 503 532 Average 2577 2185 1696 1065 393 488 631Ha Nam Binh Luc 1999 Spring 3300 2500 2100 1560 800 940 1740 2000 3259 3000 2800 1430 259 1570 1829 2001 3400 3100 2500 1500 300 1600 1900 2002 3500 2789 2015 2000 711 789 1500 Average 3365 2847 2354 1623 518 1225 1742 Kim Bang 1999 Spring 3600 3000 2600 2420 600 580 1180 2000 3200 2865 2745 1930 335 935 1270 2001 3300 2958 2436 1910 342 1048 1390 2002 3100 2859 2300 2190 241 669 910 Average 3300 2921 2520 2113 380 808 1188Ninh Binh Nho Quan 2000 Spring 2493 2300 1700 1109 193 1191 1384 2001 2400 2100 1953 1278 300 822 1122 2002 2700 1789 1450 1231 911 558 1469 2003 2612 1900 1600 712 1900 2612 Average 2551 2022 1676 1206 529 1118 1647Vinh Phuc Tam Duong 1998 Spring 2200 1800 1500 1060 400 740 1140 1999 2100 1650 1300 767 450 883 1333 2000 2300 1900 1569 1005 400 895 1295 Average 2200 1783 1456 944 417 839 1256 Vinh Tuong 1998 Spring 2400 2000 1632 1234 400 766 1166 1999 2500 1569 1354 1428 931 141 1072 2000 2800 2300 2000 1843 500 457 957 Average 2567 1956 1662 1502 610 455 1065Hoa Binh Kim Boi 1997 Spring 3743 3000 2185 1190 743 1810 2553 2000 Spring 2418 1704 1540 1160 714 544 1258 2001 3000 1330 1670 2002 Spring 3300 2600 2150 1530 700 1070 1770 Average 3115 2435 1958 1303 719 1141 1813 Tan Lac 2003 Spring 2492 2000 1771 940 492 1060 1552Vinh Phuc Tam Duong 2003 Autumn 2300 2079 1800 221 2079 2300Hoa Binh Tan Lac Autumn 2000 1712 1500 940 288 772 1060 Tan Lac 1999 Autumn 1910 1600 1400 1200 310 400 710
33
Appendix IVIrrigated peanut yield and yield gap (kg ha-1) at benchmark locations in northern Vietnam.
Farmer’s yieldDistrict
Yield gap (kg ha-1)
Expt. stn. Imp. mgt. Trad. mgt. yield I II Total
Province District Year Season 1 2 3 4 1-2 2-4 1-4
Ha Nam Duy Tien 1999 Spring 3200 2800 2400 1950 400 850 1250 2000 3500 3200 2900 2670 300 530 830 2001 3450 3000 2600 2580 450 420 870 2002 3200 2912 2500 2460 288 452 740 Average 3338 2978 2600 2415 360 563 923Ha Tay Chuong My 1999 Spring 3200 2493 2200 1250 707 1243 1950 2000 3300 2900 2700 1430 400 1470 1870 2001 3200 2956 2700 1560 244 1396 1640 2002 3300 3000 2800 1660 300 1340 1640 Average 3250 2837 2600 1475 413 1362 1775Ninh Binh Yen Khanh 2000 Spring 3600 3400 2900 2500 200 900 1100 2001 3700 3300 3000 2500 400 800 1200 2002 3569 2879 2521 2500 690 379 1069 2003 3800 2875 2523 - 925 2875 3800 Average 3667 3114 2736 2500 554 1239 1792
34
Ap
pen
dix
VW
ater
bal
ance
com
pone
nts
(mm
) of
sim
ulat
ed s
oybe
an in
sea
sona
l ana
lysi
s fo
r si
x lo
cati
ons
of w
ater
shed
.
Rai
nfal
lSu
rfac
e ru
noff
Dee
p dr
aina
geE
vapo
tran
spir
atio
nE
xtra
ctab
le w
ater
Loc
atio
nSe
ason
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Vin
h Ph
ucSp
ring
485
1471
830
29.0
1945
712
083
.945
596
253
54.9
348
519
466
7.3
3112
410
419
.7H
a N
am
494
1392
865
24.8
6134
316
848
.222
578
214
57.8
463
538
496
4.3
8825
418
822
.0N
inh
Bin
h
387
1705
772
28.4
1761
017
555
.00
404
141
71.5
353
499
445
8.3
9018
214
219
.0Ph
u T
ho
503
1876
910
30.8
3617
624
675
.517
727
112
88.1
436
563
502
7.3
5812
710
319
.0H
a Ta
y
211
1716
935
27.8
081
827
056
.20
364
163
64.0
408
561
501
7.5
9320
015
817
.7H
oa B
inh
47
217
0296
039
.140
548
230
73.5
665
825
682
.842
954
448
67.
278
173
132
21.7
Vin
h Ph
ucSu
m-A
ut65
819
3511
9227
.332
500
186
63.5
145
776
432
43.5
416
554
487
7.4
4012
180
29.1
Ha
Nam
67
224
1314
1328
.510
376
936
449
.30
941
353
62.3
433
610
500
8.3
126
251
192
15.9
Nin
h B
inh
57
626
2413
3035
.365
1020
402
59.6
494
332
069
.237
350
045
37.
710
418
215
012
.0Ph
u T
ho
748
2615
1232
30.9
121
1326
366
64.1
3467
726
455
.543
859
250
48.
464
128
9419
.9H
a Ta
y
955
2570
1466
29.0
194
1206
490
50.0
169
929
260
.144
661
153
47.
391
193
144
18.9
Hoa
Bin
h
992
1743
1354
20.7
161
537
330
39.6
165
692
383
45.1
471
577
517
6.1
100
148
124
13.5
Ap
pen
dix
VI
Wat
er b
alan
ce c
ompo
nent
s (m
m)
of s
imul
ated
pea
nut
in s
easo
nal a
naly
sis
for
six
loca
tion
s of
wat
ersh
ed.
Rai
nfal
lSu
rfac
e ru
noff
Dee
p dr
aina
geE
vapo
tran
spir
atio
nE
xtra
ctab
le w
ater
Loc
atio
nSe
ason
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Vin
h Ph
ucSp
ring
276
1271
631
31.4
943
891
98.1
041
512
677
.629
150
543
69.
445
125
9128
.7H
a N
am
442
1067
705
22.8
2926
513
342
.40
343
119
78.5
436
558
483
5.5
7624
217
124
.4N
inh
Bin
h
351
919
601
28.5
1833
212
862
.38
197
9068
.936
851
143
07.
757
180
122
27.0
Phu
Tho
41
412
7474
429
.430
417
182
58.6
040
011
891
.035
959
246
49.
144
128
9622
.6H
a Ta
y
401
1182
784
24.0
6542
821
444
.30
251
8690
.939
854
746
97.
137
198
147
27.5
Hoa
Bin
h
334
1699
763
52.5
1455
517
793
.20
631
155
125.
738
756
946
611
.032
172
110
36.3
Vin
h Ph
ucA
ut-W
in35
514
2797
227
.09
390
150
64.1
058
432
247
.433
250
144
69.
67
108
4858
.9H
a N
am
749
2056
1254
29.5
9075
734
655
.33
750
284
67.0
411
630
473
8.3
4021
014
829
.9N
inh
Bin
h
636
2288
1251
33.1
126
907
412
56.0
5884
229
959
.636
250
742
59.
147
146
110
22.7
Phu
Tho
45
021
7996
933
.561
1139
281
72.7
052
217
367
.434
956
744
59.
916
113
6637
.9H
a Ta
y
601
2114
1148
32.9
108
1034
392
57.2
053
018
975
.439
353
148
26.
628
164
8743
.4H
oa B
inh
74
214
2810
9719
.011
440
326
338
.212
654
328
246
.743
052
348
95.
820
117
6449
.7
35
Ap
pen
dix
VII
Wat
er b
alan
ce c
ompo
nent
s (m
m)
of s
imul
ated
mai
ze in
sea
sona
l ana
lysi
s fo
r si
x lo
cati
ons
of w
ater
shed
.
Rai
nfal
lSu
rfac
e ru
noff
Dee
p dr
aina
geE
vapo
tran
spir
atio
nE
xtra
ctab
le w
ater
Loc
atio
nSe
ason
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Min
Max
Mea
nC
V (
%)
Vin
h Ph
ucSp
ring
476
1460
777
28.3
1746
511
088
.632
533
182
63.7
367
581
509
8.0
1812
490
30.5
Ha
Nam
520
1372
864
23.6
5435
617
046
.70
495
160
71.9
509
627
557
4.4
5025
517
828
.6N
inh
Bin
h39
612
1773
028
.317
432
160
57.5
938
712
274
.340
256
549
08.
660
182
126
27.0
Phu
Tho
503
1895
918
33.6
4310
2524
977
.43
417
150
72.9
423
678
542
9.0
2512
893
29.8
Ha
Tay
545
1439
975
24.0
101
562
283
43.9
033
913
076
.945
663
054
46.
862
201
150
25.2
Hoa
Bin
h48
517
6692
045
.733
555
215
85.3
066
721
010
1.1
445
632
527
9.8
5515
411
232
.9V
inh
Phuc
Sum
mer
662
1994
1243
27.6
3452
920
261
.912
877
240
047
.546
863
256
26.
825
125
7342
.0H
a N
am71
024
8014
7028
.710
379
238
248
.70
912
320
71.1
525
659
583
6.5
7123
418
121
.1N
inh
Bin
h59
626
7513
6035
.566
1045
412
60.3
090
127
280
.946
759
953
27.
352
182
134
22.7
Phu
Tho
771
2643
1258
31.5
126
1348
375
64.0
162
822
666
.147
967
357
88.
437
124
7537
.3H
a Ta
y82
526
1115
2330
.419
912
2051
251
.30
677
270
65.9
523
685
608
7.5
6320
113
428
.4H
oa B
inh
1003
1800
1392
20.4
161
548
346
37.6
122
660
347
50.3
538
620
586
4.2
8814
211
416
.1
677–2005
®About ICRISAT
The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is a nonprofit,non-political organization that does innovative agricultural research and capacity building forsustainable development with a wide array of partners across the globe. ICRISAT’s mission is tohelp empower 600 million poor people to overcome hunger, poverty and a degraded environment inthe dry tropics through better agriculture. ICRISAT belongs to the Alliance of Future Harvest Centersof the Consultative Group on International Agricultural Research (CGIAR).
Contact Information
ICRISAT-Patancheru(Headquarters)Patancheru 502 324Andhra Pradesh, IndiaTel +91 40 30713071Fax +91 40 [email protected]
Liaison OfficeCG Centers BlockNASC ComplexDev Prakash Shastri MargNew Delhi 110 012, IndiaTel +91 11 32472306 to 08Fax +91 11 25841294
ICRISAT-Nairobi(Regional hub ESA)PO Box 39063, Nairobi, KenyaTel +254 20 7224550Fax +254 20 [email protected]
ICRISAT-Niamey(Regional hub WCA)BP 12404Niamey, Niger (Via Paris)Tel +227 722529, 722725Fax +227 [email protected]
ICRISAT-BamakoBP 320Bamako, MaliTel +223 2223375Fax +223 [email protected]
ICRISAT-BulawayoMatopos Research StationPO Box 776,Bulawayo, ZimbabweTel +263 83 8311 to 15Fax +263 83 8253/[email protected]
ICRISAT-LilongweChitedze Agricultural Research StationPO Box 1096Lilongwe, MalawiTel +265 1 707297/071/067/057Fax +265 1 [email protected]
ICRISAT-Maputoc/o INIA, Av. das FPLM No 2698Caixa Postal 1906Maputo, MozambiqueTel +258 21 461657Fax +258 21 [email protected]
Visit us at www.icrisat.org
®